(1) Field of the Invention
The present invention relates to a value holding system that manages a value used in a payment, and more specifically, the present invention relates to a technique for avoiding errors in managing the value.
(2) Description of the Related Art
In recent years, memory cards that have multiple functions such as a prepaid card and commuter pass functions are utilized in the field of electronic payment. A railway fare adjustment system using a memory card with a prepaid card and commuter pass functionalities is explained below as one example of the uses of such memory cards.
A railway user carries the memory card when taking a train. The user goes through an automatic ticket gate using the memory card when entering and exiting a station. When the user takes a train over a zone specified by the memory card as a commuter pass, information relating to fare adjustment is transmitted between the memory card and the automatic ticket gate. Then, an additional fare is deducted from an amount of prepaid money which is recorded in the memory card as a prepaid card, and the fare adjustment is completed.
In order to ensure security, such as a mutual authentication and encryption of the information disclosed in the below-identified patent document 1, and a verification of the memory card as disclosed in the below-identified patent document 2 are performed in the transmission of the information between the memory card and the automatic ticket gate.
In the transmission of the information, however, an issue has been noted that the automatic ticket gate accidentally requests the memory card for a payment for the same service more than once, the memory card also processes the payment more than once, and thus the amount accidentally requested by the automatic ticket gate is deducted from the memory card. Further, another issue has also been noted that the automatic ticket gate recognizes the zone which is specified by the memory card incorrectly and requests the memory card for a payment for an additional fare based on the incorrectly recognized zone, and the incorrect additional fare is deducted from the memory card.                Patent Document 1        
Japanese Published Unexamined Application No. H10-229392                Patent Document 2        
Japanese Published Examined Application No. H8-27822